React19 + Typescript fixes

[ian-wd]

• Fixes react 19 ref cleanup TS error
• Dropped global JSX usage and imports JSX type from react

React19 Cleanup function refs

Due to the introduction of ref cleanup functions, returning anything else from a ref callback will now be rejected by TypeScript. The fix is usually to stop using implicit returns, for example:

- <div ref={current => (instance = current)} />
+ <div ref={current => {instance = current}} />

The original code returned the instance of the HTMLDivElement and TypeScript wouldn’t know if this was supposed to be a cleanup function or if you didn’t want to return a cleanup function.